1. Field of the Invention
The present invention relates to a magnetic transfer master disk used in a magnetic transfer method whereby magnetic transfer is performed from a master disk carrying transfer information to a slave medium receiving the transfer and a method for manufacturing the same, and specifically relates to a magnetic transfer master disk that is favorable for magnetically transferring magnetic information pattern such as format information to a magnetic disk used in such as a hard disk device, and a method for manufacturing the same.
2. Description of the Related Art
Magnetic disks (hard disks) are used in hard disk drives that have been rapidly prevailing in recent years. Ordinarily, after delivering a magnetic disk from a magnetic disk manufacturer to a drive manufacturer, format information and address information are written in the magnetic disk before incorporating the magnetic disk in a drive. Although this writing can be performed by means of a magnetic head, a method that performs collective transfer from a master disk with such format information and address information written therein is efficient and preferable.
In this magnetic transfer technique, a master disk and a disk on which transfer is performed (slave disk) are brought into close contact with each other, a magnetic field generation device, such as an electromagnet device, a permanent magnet device and so on, is provided to one or both sides of the disks to apply a magnetic field for transfer, thereby transferring a magnetization pattern corresponding to information the master disk has (e.g., servo signals).
As an example of a master disk used for such magnetic transfer, a master disk obtained by forming a pattern of protrusions/recesses corresponding to information signals on a surface of a substrate and coating the surface of this protrusion/recess pattern with a thin-film magnetic layer has been proposed (See, e.g., Japanese Patent Application Laid-Open Nos. 2001-256644 and 2006-216181).
This protrusion/recess pattern of the master disk is formed by duplicating protrusions/recesses on a surface of a substrate, using a metal disk as a master. The metal disk is manufactured by applying a laser or electron beam that has been modulated according to information to a silicon (Si) primitive plate coated with a photoresist while rotating the primitive plate, forming a conductive layer on the surface of the primitive plate having protrusions/recesses, obtained as a result of developing the photoresist, by means of, e.g., sputtering, and then, performing plating (electroforming) on this conductive layer to obtain a metal mold, and removing the metal mold from the plate.
A magnetic transfer master disk requires a magnetic layer formed of a material with high magnetic permeability, and in the technique disclosed in Japanese Patent Application Laid-Open No. 2006-216181, a magnetic layer doubles as a conductive layer for electroforming.